208 



entery. The pulmouary circulation develops late and nine weeks after 

 the time of hatching is indicated only by a small pulmonary vein 

 opening into the auricle. 



These are a few of the more important facts regarding the 

 development of the vascular and respiratory systems of Ceratodus. 

 Summing up I should say that the resemblances in the vascular and 

 respiratory systems between Ceratodus, the most primitive of the 

 Dipnoi, and the Amphibia, especially the Urodela, are numerous and 

 fundamental and can not be explained as parallelisms. 



Barnard College, Columbia University, November 23, 1904. 



Nachdruck verboten. 



The Eye of Bdellostoma Stouti. 



By Bennet Mills Allen, 

 Department of Anatomy, University of Wisconsin. 



With 11 Figures. 



The eye of Bdellostoma Stouti was first studied by Johannes 

 Müller^), who noted the absence of eye-muscles, the lack of a 

 crystalline lens, the homogeneous character of the eye capsule and 

 the total absence of pigmentation in the eye structures. As little or 

 nothing had since been published upon this subject, it seemed desirable 

 to carry the work further by means of serial sections. 



The material for this work consisted in nineteen adult specimens 

 of both sexes and of but slightly varying length (2 cm above or 

 below 45 cm). The fish were preserved entire in Müller's fluid. The 

 eyes were removed together with the surrounding tissues, care being 

 taken to cut the tissues in such a manner as to permit of accurate 

 orientation. Series of sections were cut in paraffine and stained with 

 various stains, chiefly Heidenhain's iron-alum-haematoxylin. 



The eye is imbedded in a mass of fat lying beneath a transparent 

 patch of skin on the side of the head. No traces of eye-muscles are 

 to be seen. Kupffer^) states that they are not present in embryonic 

 life. A slender optic nerve can be traced through the mass of fat to 



1) J. Müller, Vergleichende Anatomie der Myxinoiden, 1833 — 1843. 



2) K. V. KuPFFER, Studien zur vergleichenden Entwickelungs- 

 geschichte der Kranioten. Heft 4. Zur Kopfentwickelung von Bdello- 

 stoma. 



